The primary objective for the study is to test the hypothesis that sertraline plus alprazolam XR will result in superior early stabilization of primary care PD patients versus sertraline/placebo over a 12-week treatment period. The secondary objectives of the study are a) to assess withdrawal symptoms during alprazolam XR taper (weeks 5-7 of the 12-week trial) and after discontinuation, b) to compare physical health outcomes, medical services utilization, and cost-effectiveness of the two study interventions across the 12-week treatment period and subsequent three month maintenance treatment with sertraline alone, and c) to assess whether early co-administration of sertraline/ alprazolam XR will result in greater maintenance of treatment response than sertraline/placebo over the three months following the 12 week acute treatment program.